TWI824665B - Adhesive film for wafer back grinding - Google Patents

Abstract

An adhesive film for wafer back grinding is provided in the present invention. The adhesive film for wafer back grinding comprises: a multilayer substrate including an upper base material layer and a lower base material layer; a first adhesive layer disposed on the upper base material layer; and a second adhesive layer disposed between the upper base material layer and the lower base material layer. The second adhesive layer is formed of an adhesive composition comprising a light-transmitting adhesive resin and light scattering particles, and the second adhesive layer satisfies the following formula 1. The refractive index of the above-mentioned light scattering particles is 1.42 to 1.60, which reduce or suppress the generation of adhesive residues in the back grinding process of the wafer, and has an excellent buffering effect on the surface of the wafer, and also improves the uniformity of wafer thickness after the back grinding process. Formula 1: 0.05≤|A-B|≤0.2, wherein A is the refractive index of the light-transmitting adhesive resin, and B is the refractive index of the light scattering particles.

Description

Adhesive film for wafer backside grinding

The present invention relates to an adhesive film, which is used to protect the wafer during the back grinding (wafer back grinding) or wafer lapping (wafer thinning) process. Used on the surface. More specifically, the present invention relates to an adhesive film for wafer back grinding that is used by reducing or eliminating the residue of the adhesive when removing (peeling off) the adhesive film after performing a wafer back grinding process ( The production of residue) makes the processability very excellent.

With the development of technology in recent years, semiconductor chips are required to be smaller, denser, and thinner. Therefore, wafers are also required to be thinner. A typical method for thinning a wafer chip is to reduce the thickness by grinding the backside of the wafer. The grinding process can be performed according to the type or specification of the electronic device using the semiconductor chip to achieve thinning of the wafer.

Since the back grinding of a semiconductor chip wafer is a process of applying physical impact, in order to protect the surface of the wafer, the back grinding of the wafer is usually performed with an adhesive film for wafer back grinding attached. This adhesive film includes a base material and an adhesive layer used to bond the wafer surface. For buffering effect, a buffer layer or impact-absorbing layer is usually formed on the back of the base material. Furthermore, the adhesive layer is usually formed of an energy ray curable adhesive composition.

Furthermore, in order to remove the adhesive film used in the wafer back polishing process from the wafer surface after back polishing the wafer, energy rays are irradiated to reduce the adhesive force and peel off.

On the other hand, with the rapid development of information communication technology and market expansion in recent years, the demand for semiconductor devices has gradually increased in density. As a result, the thickness of the active layer (active layer) disposed on the wafer surface increases, and the unevenness (or pattern) of the active layer also gradually increases. Therefore, when the adhesive film for wafer back polishing is peeled off, energy beam curing may not fully proceed in the shadow area caused by the unevenness of the active layer. As a result, since the adhesive force of the adhesive film used for wafer back grinding is not sufficiently reduced, the peeling force is reduced. Therefore, adhesive residue derived from the adhesive film easily remains on the wafer surface, hindering processability, and ultimately affecting the prepared semiconductor chip. quality is adversely affected, and there are technical requirements to address the problem.

The object of the present invention is to provide an adhesive film for wafer back grinding. Even if there are large uneven portions on the wafer or the active layer on the wafer surface, after the wafer back grinding process, when the wafer back grinding adhesive film is peeled off, When bonding the film, it can also reduce or inhibit the generation of adhesive residue.

The object of the present invention is not limited to the above-mentioned objects. Other objects and advantages of the present invention that are not mentioned can be understood through the following description and can be understood more clearly through the embodiments of the present invention. Furthermore, it can be seen that the objects and advantages of the present invention can be achieved by the solutions and combinations thereof shown in the scope of the claimed invention.

In order to solve the above technical problems, according to an embodiment of the present invention, an adhesive film for wafer backside grinding can be provided, which is characterized in that it includes: a multi-layer base material, including an upper base material layer and a lower base material layer; a first adhesive film layer, disposed on the above-mentioned upper base material layer; and a second adhesive layer, disposed between the above-mentioned upper base material layer and the lower base material layer, the above-mentioned second adhesive layer is composed of an adhesive layer containing a translucent adhesive resin and light scattering particles. A composition is formed and satisfies the following formula 1. The refractive index of the above light scattering particles is 1.42~1.60.

In the above formula 1, A is the refractive index of the translucent binder resin, and B is the refractive index of the light scattering particles.

The above-mentioned light scattering particles may be included in 0.1 to 10 parts by weight relative to 100 parts by weight of the above-mentioned adhesive composition of the second adhesive layer.

The light scattering particles may include at least one type of inorganic particles and organic particles.

The average particle diameter of the above-mentioned light scattering particles may be 1 μm ~ 50 μm.

The inorganic particles may include at least one selected from the group consisting of silica particles, glass powder, and quartz particles.

The above-mentioned organic particles may include particles selected from the group consisting of acrylic resin particles, polystyrene resin particles, styrene-acrylic acid copolymer components, polyethylene resin particles, epoxy resin particles, silicone resin particles, polyvinylidene fluoride particles, and polytetrafluoroethylene. One or more of the group consisting of ethylene particles, divinylbenzene resin particles, phenol resin particles, urethane resin particles, cellulose acetate particles, nylon particles, cellulose particles, benzinated melamine resin particles and melamine resin particles.

The total light transmittance of the adhesive film for wafer backside grinding of the present invention can be more than 70%, and the diffuse transmittance can be more than 6%.

The thickness of the above-mentioned first adhesive layer may be 10 μm~100 μm, and the thickness of the above-mentioned second adhesive layer may be 10 μm~100 μm.

The above-mentioned lower base material layer and the upper base material layer may respectively comprise polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, fully aromatic polyester, poly One or more of the group consisting of imine, polyamide, polycarbonate, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polystyrene, polyetherketone and biaxially oriented polypropylene, preferably , the lower base material layer and the upper base material layer may be formed of polyethylene terephthalate.

The first adhesive layer may be formed of an adhesive composition including an acrylic adhesive resin.

The translucent adhesive resin of the second adhesive layer may include translucent acrylic adhesive resin.

The shear storage modulus of the above-mentioned second adhesive layer under the temperature condition of 30°C may be 0.05MPa~5.00MPa.

A primer layer may be further provided on at least one of the upper surface of the upper base material layer, the lower surface of the upper base material layer, and the upper surface of the lower base material layer.

When the adhesive film for wafer back grinding of the present invention is applied to the back grinding process, even if there are large uneven portions on the wafer or the active layer on the wafer surface, it can have excellent adhesion to the wafer surface. Concave-convex embedding properties can improve the wafer processing process and the quality of the prepared semiconductor chips by reducing or inhibiting the generation of adhesive residues when peeling off the adhesive film for wafer back grinding after the wafer back grinding process.

Furthermore, when the adhesive film for wafer back grinding of the present invention is applied to the back grinding process, it can have an excellent buffering effect (or protective effect) on the surface of the wafer, and can also improve the wafer strength after the back grinding process. Uniformity of thickness of circle.

The effects of this specification are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those with ordinary knowledge in the art from the following description. Hereinafter, the above effects and specific effects of the present invention will be described while describing specific details for implementing the present invention.

10: First adhesive layer

20: Upper base material layer

30:Second adhesive layer

40: Lower base material layer

100: Adhesive film for wafer backside grinding

200: Wafer before back grinding process

210: Wafer after back grinding process

300:Active layer

S1-S5: Steps

P: light scattering particles

R: Residue area of adhesive

FIG. 1 schematically shows a flow chart of applying an adhesive film for wafer back polishing according to an embodiment of the present invention to a wafer back polishing process and a subsequent peeling process.

FIG. 2 shows a cross-sectional view of an adhesive film for wafer backside polishing according to one embodiment of the present invention.

The aforementioned objects, features, and advantages will be described in detail with reference to the accompanying drawings, whereby those of ordinary skill in the technical field to which the present invention belongs can easily implement the technical idea of the present invention. In describing the present invention, if it is judged that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. As follows, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numbers are used to represent the same or similar structural elements.

In this specification, any structure arranged "upper (or lower)" of a structural element or "upper (or lower)" of a structural element does not only mean that any structure is in contact with the upper surface (or lower surface) of the above structural element. Arrangement also means that other structures can be interposed between the above-mentioned structural elements and any structure arranged on (or below) the above-mentioned structural elements.

Unless otherwise expressly mentioned in this specification, singular expressions used in this specification include plural expressions. In this application, terms such as "consisting of" or "includes" should not be interpreted as necessarily including all the various structural elements recorded in the specification, but should be interpreted as not including some of the structural elements, or may also include Includes additional structural elements.

In this specification, terms such as "one side", "the other side", and "both sides" are used to distinguish a certain structural element from other structural elements, and structural elements are not limited to the above terms.

In the description of this specification, "(meth)acrylate" is used as a term including "acrylate" and "methacrylate", and the same applies to similar terms.

In the following description of the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.

FIG. 1 schematically illustrates a flow chart of a process in which an adhesive film 100 for wafer back polishing according to an embodiment of the present invention is applied to a wafer, and the adhesive film is peeled off by irradiating energy rays after back polishing.

Specifically, S1 in FIG. 1 is the step of preparing the wafer (loading the wafer) before the wafer back grinding process. It shows that the active layer 300 is disposed on the surface of the wafer 200. The active layer 300 may include The base material layer of the unevenness (pattern) on the wafer surface.

S2 in FIG. 1 is a step of adhering (or attaching) the adhesive film 100 for wafer back grinding of the present invention to the surface side of the wafer, thereby protecting the surface of the wafer 200 during back grinding and/or The role of active layer 300.

S3 of Figure 1 briefly illustrates the steps of performing a back grinding process. In the back grinding process, a variety of back grinding equipment used in this technical field can be used without limitation, for example, it can be used on a chuck table. Equipment that can rotate the grinding wheel after loading the wafer. On the other hand, the thickness of the wafer before the back grinding process is approximately in the range of 700μm~900μm. After the back grinding process, Depending on the specifications of the electronic equipment to which semiconductor chips are applied, the thickness of the final wafer can be reduced to a range of approximately 30 μm to 300 μm.

S4 of FIG. 1 schematically shows the step of irradiating energy rays (typically ultraviolet (UV)) in order to peel off the adhesive film 100 for back grinding of the wafer after the back grinding process. Compared with the wafer 200 before the back grinding process, the back grinding The thickness of the wafer 210 after the process is reduced. Therefore, the adhesive layer of the adhesive film 100 for wafer back polishing is usually formed of an energy ray curable adhesive composition.

S5 in FIG. 1 briefly illustrates the step of peeling off the adhesive film 100 for wafer backside polishing after the backside polishing process. In this case, if the exposure of energy rays reaching the adhesive film 100 for wafer back polishing is insufficient, the adhesive force cannot be sufficiently reduced to the extent that good peeling is possible, and therefore the wafer back grinding may remain in the peeling step. Use the residue of Adhesive Film 100. As mentioned above, FIG. 1 illustrates the adhesive residue remaining area (R).

If residues of the adhesive film 100 for wafer back polishing remain on the wafer, problems may arise that may adversely affect processability and the quality of the semiconductor chip produced. Furthermore, as the degree of unevenness (pattern) of the active layer 300 disposed on the wafer 200 or the wafer surface becomes deeper, the shadow areas that cannot be reached by energy rays increase, so the above problem is further deepened.

The inventor of the present invention focused on the above-mentioned problems, and in order to allow the exposure of energy rays to fully reach the adhesive film for wafer back polishing, light scattering particles P were added to the second adhesive layer 30 of the adhesive film for wafer back polishing 100 .

In this way, since the second adhesive layer 30 is formed of an adhesive composition including a translucent adhesive resin and light scattering particles P, it can exhibit a light scattering effect. Therefore, it was found that the irradiated energy rays can be uniformly dispersed in the adhesive film 100 for wafer back polishing, and the above-mentioned problem of insufficient exposure can be solved, and the present invention was completed.

Therefore, as shown in Figure 2, the adhesive film for wafer backside grinding of the present invention has the following structure, which includes: a multi-layer base material, including an upper base material layer 20 and a lower base material layer 40; a first adhesive layer 10 configured on the upper base material layer 20; and a second adhesive layer 30 disposed between the upper base material layer 20 and the lower base material layer 40. The second adhesive layer 30 can be made of a translucent adhesive resin and light scattering particles. The adhesive composition of P is formed.

Below, the characteristics of the adhesive film for wafer backside polishing and the structure of each layer are described in detail.

multilayer substrate

The multi-layer substrate includes a lower substrate layer 40 , an upper substrate layer 20 and a second adhesive layer 30 . The first adhesive layer 10 is arranged on the upper base material layer 20 , and the second adhesive layer 30 is arranged between the lower base material layer 40 and the upper base material layer 20 . In the adhesive film for wafer back polishing of the present invention, the multilayer base material has a sandwich structure in which the second adhesive layer 30 is arranged between the lower base material layer 40 and the upper base material layer 20 .

The lower base material layer 40 and the upper base material layer 20 may be formed of a material with a high tensile elastic modulus. More specifically, the lower base material layer 40 and the upper base material layer 20 may have a tensile elastic modulus of 1000 MPa or more, such as 1200 MPa or more, 1500 MPa or more, 2000 MPa or more, 3000 MPa or more. In this case, the tensile elastic modulus is The measured value under the temperature condition of 23°C is the basis.

When the tensile elastic modulus of the lower base material layer 40 and the upper base material layer 20 is relatively low, less than 1000 MPa, due to the low support force for the wafer or semiconductor chip, it is possible to perform the back grinding process (back grinding process). ) produces a collision of semiconductor chips.

The lower base material layer 40 and the upper base material layer 20 may respectively comprise polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate ( PBT), fully aromatic polyester and other polyimide (PI), polyamide (PA), polycarbonate (PC), polyacetal, modified polyphenylene ether, polyphenylene sulfide, polypropylene, One or more of the group consisting of polyetherketone and biaxially oriented polypropylene (Oriented Poly-propylene).

Furthermore, the lower base material layer 40 and the upper base material layer 20 may be formed of the same material. For example, the lower base material layer 40 and the upper base material layer 20 may be formed of polyethylene terephthalate (PET) material.

The thickness of the lower base material layer 40 and the upper base material layer 20 is not particularly limited, and they may have the same thickness. For example, the lower base material layer 40 and the upper base material layer 20 may each have a thickness of about 10 μm ~ 150 μm. On the other hand, in the present invention, since the lower base material layer 40 and the upper base material layer 20 can have high tensile elastic modulus, when the lower base material layer 40 and the upper base material layer 20 , especially the upper base material layer 20 If the thickness is too thick, it may be susceptible to impact during the back grinding process. Therefore, for example, the thickness of the lower base material layer 40 and the upper base material layer 20 may be about 150 μm or less, but is not limited thereto.

On the other hand, according to the needs of the lower base material layer 40 and/or the upper base material layer 20, a small amount of various additives, such as coupling agent, plasticizer, antistatic agent, antioxidant, etc., may be included.

first bonding layer

In FIG. 2 , the first adhesive layer 10 is the part that is bonded (or adhered) to the wafer. The first adhesive layer 10 is not particularly limited as long as it has appropriate adhesiveness under normal temperature conditions. It can be made of an acrylic adhesive composition, a silicon adhesive composition, a polyester adhesive composition, which are known ultraviolet (UV) curing adhesive compositions. It is formed from various adhesive compositions such as polyamide adhesive composition, urethane adhesive composition, styrene-diene block copolymer adhesive composition, etc. Preferably, it can be formed from an acrylic adhesive composition. .

For example, the first adhesive layer 10 may be formed of an adhesive composition including an acrylic adhesive resin. The acrylic adhesive resin may be a polymer of a (meth)acrylic monomer having an alkyl group with a carbon number of 1 to 14. Specifically, Preferably, one or more polymers from the group consisting of ethylhexyl acrylate, butyl acrylate, ethyl acrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate and hydroxybutyl acrylate can be selected. It may be a polymer containing monomers polymerized, including monomers bonded to a carboxyl group or a hydroxyl group.

Furthermore, the adhesive composition used to form the first adhesive layer 10 may also include a photopolymerization initiator and a cross-linking agent, which are not particularly limited as long as they are commonly used in this technical field.

The above-mentioned cross-linking agents play a role in increasing the cohesion of the adhesive composition, and more than one cross-linking agent can be mixed and used, for example, isocyanate cross-linking agents, epoxy cross-linking agents, aziridine cross-linking agents and metal chelates Compound cross-linking agents, etc.

The above-mentioned photopolymerization initiator is a substance that initiates the reaction of the ultraviolet curing cross-linking agent by ultraviolet irradiation. The type and content of the photopolymerization initiator are appropriately selected and used in consideration of the curing speed of the resin composition. It can be obtained by mixing one or more photopolymerization initiators. use. For example, hydroxycyclohexylphenylketone (Irgacure 184), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propan-1-one (2- methyl-1[4-(methythio)phenyl]-2-morpholino-propan-1-on; Irgacure 907), α,α-methoxy-α-hydroxyacetophenone (α,α-methoxy-αhydroxyacetophenone; Irgacure 651) and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (2-hydroxy-2-methyl-1-phenyl-propan-1-one; Irgacure 1173), etc.

On the other hand, the thickness of the first adhesive layer 10 is not particularly limited. For example, the thickness may be about 10 μm ~ 100 μm.

Although not shown in FIG. 2 , it may also include a release film disposed on the upper surface of the first adhesive layer and bonded through the first adhesive layer. One side of the above-mentioned release film can be subjected to release treatment. The above-mentioned release treatment can be used without restriction as long as it is a substance commonly used for release treatment in this field. For example, preferably, silicone is used for release treatment.

Second bonding layer

In FIG. 2 , the second adhesive layer 30 is disposed between the upper base material layer 20 and the lower base material layer 40 , and functions as a buffer layer that can alleviate the impact of the wafer and a light diffusion with light scattering effect during the back grinding process. layer.

In this way, in order to have a buffering effect, the lower the shear storage modulus of the second adhesive layer 30 of the present invention, the more advantageous it is. However, when the shear storage modulus is too low, during the back grinding process, with the temperature The rise of the buffer layer may cause problems such as flow or uneven thickness of the buffer layer at high temperatures. Considering the above problems, preferably, the shear storage modulus of the second adhesive layer 30 under the temperature condition of 30°C is 0.05MPa~5MPa, more preferably, 0.05MPa~3MPa, most preferably, 0.05 MPa~2.5MPa. The present invention includes the second adhesive layer 30 The adhesive film 100 for wafer back grinding has the advantage of excellent buffering effect on the surface of the wafer, and can also improve the thickness uniformity of the wafer after the back grinding process.

Furthermore, the second adhesive layer 30 of the present invention can be formed from an adhesive composition including a translucent adhesive resin and light scattering particles P, and therefore serves as a light diffusion layer that provides a light scattering effect. Due to the light scattering effect of the second adhesive layer 30 as described above, the energy rays irradiated for peeling off the adhesive film for back polishing of the wafer are evenly dispersed, thereby reducing or suppressing the generation of adhesive residue during peeling, and excellently improving the Processability and quality of prepared semiconductor chips. Moreover, the adhesive composition used to form the second adhesive layer 30 can be mixed with more than one cross-linking agent as needed, such as metal chelate cross-linking agents, isocyanate cross-linking agents, epoxy cross-linking agents, etc. .

Therefore, in order to make the second adhesive layer 30 exhibit the scattering effect, it is deduced through experiments that the difference in the refractive index of the translucent adhesive resin and the light scattering particles P is preferably 0.05~0.2. This relationship can be embodied by the following formula 1 .

In the above formula 1, A is the refractive index of the translucent binder resin, and B is the refractive index of the light scattering particles.

Furthermore, based on 100 parts by weight of the adhesive composition for forming the second adhesive layer 30 of the present invention, it is preferred to include 0.1 to 10 parts by weight of the light scattering particles P. If the content of the light scattering particles P is less than 0.1 parts by weight, the light scattering effect may not be sufficient. Moreover, if the content of the light scattering particles P is greater than 10 parts by weight, the total light transmittance is reduced, and the curing based on energy rays cannot be performed to the required extent during the peeling process, reducing adhesion. The effectiveness of agent residues may not be sufficient as the inclusion of excess particles may adversely affect the uniformity of the wafer after the wafer back grinding process.

Hereinafter, the translucent adhesive resin and the light scattering particles P included in the second adhesive layer 30 will be described in detail.

light scattering particles

The above-mentioned light scattering particles P are particles for diffusing or scattering light. Preferably, they are transparent particles with light transmittance. As long as the light transmittance is high, they are not necessarily colorless and may be colored. Furthermore, in order to make the light scattering effect uniform, it is preferable that the light scattering particles P have a sphere shape, and in order to have high light transmittance, it is preferable that the refractive index of the above light scattering particles P is between 1.42 and 1.60. within the range.

Furthermore, the average particle diameter of the light scattering particles P is preferably 1 μm to 50 μm, more preferably 1 μm to 10 μm. When the average particle size is less than 1 μm, the light diffusion effect or light scattering effect is low. When it is larger than 50 μm, the thickness uniformity of the second adhesive layer 30 and the adhesive film 100 for wafer back grinding may be affected because the particles are too coarse. reduce. On the other hand, the above-mentioned average particle diameter is measured based on the coulter counter method. Although in order to improve uniformity, it is preferable that the average particle diameter of the light scattering particles P is usually uniform, in order to adjust the diffusion characteristics, two or more types of light scattering particles P of different materials or particle sizes may be mixed and used.

As long as the plurality of conditions described above are satisfied, the type of the light scattering particles P is not particularly limited, and may include at least one type of inorganic particles and organic particles. The inorganic particles may include at least one selected from the group consisting of silica particles, glass powder, and quartz particles. The above-mentioned organic particles may include acrylic resin particles, polystyrene Resin particles, particles of styrene-acrylic copolymer components, polyethylene resin particles, epoxy resin particles, silicone resin particles, polyvinylidene fluoride particles, polytetrafluoroethylene particles, divinylbenzene resin particles, phenol resin particles, One or more types from the group consisting of urethane resin particles, cellulose acetate particles, nylon particles, cellulose particles, benzoguanamine resin particles and melamine resin particles.

Translucent adhesive resin

In order for the second adhesive layer 30 of the present invention to function as a light diffusion layer, the adhesive resin forming the second adhesive layer 30 may be selected from translucent adhesive resins.

For example, preferably, the refractive index of the translucent adhesive resin is in the range of 1.40 to 1.70, and more preferably, in the range of 1.45 to 1.55.

The above-mentioned translucent adhesive resin is not particularly limited as long as it is a translucent resin material, such as translucent thermoplastic resin, thermosetting resin, or photocurable resin. For example, normal temperature pressure-reduced adhesive resins can be used, such as polyethylene resin, polypropylene resin, cycloolefin resin, polyester resin, epoxy resin, polyurethane resin, silicone resin, and acrylic resin, or, Resins that do not have room temperature pressure reduction adhesive properties, such as polymethyl methacrylate resin, polycarbonate resin, polyethylene terephthalate resin, and polyvinyl chloride resin, can also be used.

Preferably, in the present invention, an acrylic adhesive resin can be used as the translucent adhesive resin. For example, the acrylic adhesive resin can be a homopolymer or copolymer of acrylic monomers, such as acrylic acid and its esters, methacrylic acid and its esters, acrylamide, acrylonitrile, etc., and can be the above-mentioned acrylic monomers. At least one copolymer with a vinyl monomer, such as vinyl acetate, maleic anhydride or styrene. And, by further With monomers selected from the group consisting of adhesive monomers, such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, etc.; monomers used as cohesion components, such as vinyl acetate, acrylamide, acrylonitrile, and styrene. and methacrylate, etc.; functional group-containing monomers that can improve adhesion, such as acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, hydroxyethyl methacrylate, hydroxypropyl methacrylate, methyl Dimethylaminoethyl acrylate, hydroxymethylacrylamide, glycidyl methacrylate, etc.; copolymerization of one or more of the group consisting of fluorine-containing acrylates or sulfur-containing acrylates used to adjust the refractive index as acrylics Adhesive resin is used.

On the other hand, the thickness of the second adhesive layer 30 is not particularly limited. For example, the thickness may be about 10 μm ~ 100 μm.

Adhesive film for wafer backside grinding

Preferably, the total light transmittance of the adhesive film 100 for wafer back polishing of the present invention is more than 70%, and the diffuse transmittance is more than 6%.

Specifically, in order to peel off the wafer back polishing adhesive film 100 from the wafer and reduce the adhesive force, a curing reaction is performed by irradiating energy rays (typically ultraviolet rays). In this case, the curing reaction based on energy rays can be fully carried out, and preferably, the total light transmittance is 70% or more.

On the other hand, since the second adhesive layer 30 of the present invention includes the light scattering particles P, the light scattering or light diffusion effect is manifested in the overall structure of the adhesive film 100 for wafer back grinding. In order to fully demonstrate the light scattering or light diffusion effect, it is preferable that the diffuse transmittance of the entire structure of the adhesive film 100 for wafer back polishing is 6% or more.

Below, the structure and function of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the invention and should not be It should not be construed as limiting the invention in any sense. Contents not described here can be fully deduced technically by a person with ordinary knowledge in the technical field, and therefore the description thereof is omitted.

Preparation Example 1: Preparation of the first adhesive composition for forming the first adhesive layer

A monomer mixture consisting of 27 grams of n-butyl acrylate (BA), 48 grams of methyl acrylate (MA) and 25 grams of hydroxyethyl acrylate (HEA) was put into the reactor, and a cooling device was set up in the reactor to Nitrogen reflux and easy temperature adjustment.

Next, 100 parts by weight of ethyl acetate (EAc) as a solvent was added to 100 parts by weight of the above-mentioned monomer mixture. In order to remove oxygen in the above-mentioned reactor, nitrogen gas was injected and sufficient temperature was maintained at 30°C. Mix for 30 more minutes. Thereafter, the temperature was raised to 50°C and maintained, and azobisisobutyronitrile with a concentration of 0.1 parts by weight was added as a reaction initiator to start the reaction, and then polymerized for 24 hours to prepare a first reactant.

24.6 parts by weight of 2-methacryloyloxyethyl isocyanate (MOI) and 1 part by weight of the catalyst (dibutyl tin dilaurate (DBTDL: dibutyl tin dilaurate)) relative to the MOI were combined with the first reactant , an acrylic adhesive resin with a weight average molecular weight of 500,000 was obtained by reacting at a temperature of 40°C for 24 hours.

Based on 100 parts by weight of the above-mentioned acrylic adhesive resin, 0.1 parts by weight of Irgacure 184 (BASF Company) as a photopolymerization initiator and 2 parts by weight of an isocyanate cross-linking agent (Japan Polyurethane Industry Co., Ltd.) as a cross-linking agent were added (Nippon Polyurethane Kogyo Co., Ltd., trade name "Coronate C"), and then mix thoroughly to prepare a first adhesive composition for forming a first adhesive layer.

Preparation Example 2: Preparation of the second adhesive composition for forming the second adhesive layer

By adding 20 parts by weight of butyl acrylate, 10 parts by weight of ethylhexyl acrylate, 55 parts by weight of methyl acrylate, 7 parts by weight of 2-hydroxyethyl acrylate, 8 parts by weight of acrylic acid, 0.05 parts by weight of even The mixture obtained by mixing nitrogen bisisobutyronitrile and 100 parts by weight of ethyl acetate was polymerized in a nitrogen atmosphere and a temperature of 60° C. for 6 hours to obtain an acrylic adhesive resin with a weight average molecular weight of 600,000.

Based on 100 parts by weight of the above-mentioned acrylic adhesive resin, after adding 3 parts by weight of isocyanate cross-linking agent (prepared by Nippon Polyurethane Kogyo Co., Ltd., trade name "Coronate C") , mix thoroughly to prepare a second adhesive composition for forming a second adhesive layer.

The refractive index of the second adhesive composition prepared above was measured to be 1.48, and the refractive index was measured by using an Abbe refractometer.

Example 1

By coating the first adhesive composition of Preparation Example 1 on the release-treated PET (polyethylene terephthalate film, thickness 50 μm), the thickness of the first adhesive layer reaches 20 μm, and the thickness of the first adhesive layer is reduced to 50 μm. Thick biaxially stretched polyethylene terephthalate (PET) film (substrate) was bonded to prepare a first composite film with a first adhesive layer having a thickness of 120 μm.

Next, based on 100 parts by weight of the second adhesive composition of Preparation Example 2, 1.0 parts by weight of polystyrene component organic particles (weighed as light scattering particles) having a refractive index of 1.59 and an average particle diameter of 3 μm were added. For "b1"), mix thoroughly and apply On a biaxially stretched polyethylene terephthalate (PET) film with a thickness of 25 μm, so that the thickness reaches 20 μm, a second composite film having a second adhesive layer with a thickness of 45 μm was prepared.

An adhesive film for wafer backside polishing with an overall thickness of 115 μm (the overall thickness does not include the thickness of the release-type PET) was prepared by joining the first composite film and the second composite film.

Example 2 and Example 3 and Comparative Examples 1 to 3

In Example 1, an adhesive film for wafer backside polishing was prepared in the same manner as in Example 1, except that the type or content of each component, the thickness of the adhesive layer, etc. were changed to Table 1 below.

Experimental Example 1: Optical Characteristics Evaluation

With respect to the adhesive films for wafer back polishing of Examples 1 to 3 and Comparative Examples 1 to 3, the overall transmittance ( T.T, %) and diffuse transmittance (D.T, %), and its structure is shown in Table 1.

Experimental Example 2: Determination of the Shear Storage Modulus of the Second Adhesive Layer

Using a rheometer (Rheometer, TA Instruments; ARES-G2) as a shear storage modulus measuring device, the materials used to form the above-described Examples 1 to 3 and Comparative Examples 1 to 3 were stacked. The wafer backside is ground to obtain a single-layer adhesive layer formed by the second adhesive composition solution of the second adhesive layer of the adhesive film to obtain a sample with a size of 8 mm in diameter × 1 mm in thickness, and the temperature environment is from -20°C to 120°C at 1Hz. The shear storage modulus was measured at a temperature of 30°C and recorded in Table 1 below.

Experimental Example 3: Thickness uniformity and residue test after wafer backside grinding

After the adhesive films for wafer back polishing in Examples 1 to 3 and Comparative Examples 1 to 3 were adhered to the semiconductor circuit surface (= wafer surface), back polishing equipment (DISCO; DGP8760) was used. Wafers with a thickness of 725 μm were back ground to a thickness of 100 μm.

After the back grinding process is completed, the exposure equipment (Shiming VACTRON; TRSJ-3000) is used to irradiate 300mJ/cm2 of ultraviolet A. Then, heat sealing tape (MBS-100R) is thermocompressed on one side of the peripheral portion of the adhesive film for wafer back polishing under a temperature condition of 220°C, and then the adhesive film for wafer back polishing is removed.

After the back grinding process, observe 20 points on the wafer surface with the adhesive film removed through a microscope to confirm the thickness uniformity of the wafer and whether adhesive residue is produced. The specific method is as follows.

1. Adhesive residue testing

The size of the residues at 20 points in the back-polished wafer was measured and evaluated as follows. The results are shown in Table 1 below.

○: No residue with a size of 10 μm or less

△: Residues with a size of 10 μm or less are generated

×: Residues with a size of 10 μm or more are produced in large quantities

2. Wafer thickness uniformity test

When the standard deviation of the thickness of 20 points in the back-ground wafer is ±4 μm or less, the thickness uniformity of the wafer is evaluated as good (○). When the tolerance is ±6 μm or more, the thickness uniformity of the wafer is evaluated as poor (×), and its structure is shown in Table 1 below.

b1 to b3 of the above-mentioned Table 1 are as follows.

-b1: As light scattering particles, the polystyrene component has a refractive index of 1.59 and an average particle diameter of 3 μm.

-b2: As light scattering particles, the polytetrafluoroethylene component has a refractive index of 1.42 and an average particle diameter of 3 μm.

-b3: As light scattering particles, the polymethyl methacrylate component has a refractive index of 1.49 and an average particle diameter of 3 μm.

It can be seen from the above Table 1 that in Embodiment 1 to Embodiment 3 of the present invention, the second adhesive layer functions as a buffer layer and has a protective effect during back grinding of the wafer. At the same time, by including light in the second adhesive layer Scattering particles also show excellent results in adhesive residue testing and thickness uniformity testing.

In contrast, the second adhesive layer in Comparative Example 1 did not contain light scattering particles, and a large amount of residues with a size of 10 μm or more were generated in the adhesive residue test. Comparative Example 2 contains excessive light scattering particles and also shows poor results in the adhesive residue test and thickness uniformity test. The shear storage modulus of the second adhesive layer is higher than that of the Example. In Comparative Example 3, the difference in refractive index between the adhesive resin used to form the adhesive layer and the light scattering particles is too low. Since Formula 1 is not satisfied, the light scattering (diffusion) effect is insufficient, resulting in 10 μm in the adhesive residue test results. The effect of inhibiting the generation of residues is unsatisfactory due to residues of the following sizes.

As described above, although the present invention has been described with reference to the illustrative drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification. It is obvious that a person of ordinary skill can understand the technical idea of the present invention. A variety of deformations can be achieved within the range. Furthermore, even if the effects of the structure of the present invention are not explicitly described in the first description of the embodiments of the present invention, it should be recognized that the effects can be predicted by the corresponding structure.

100: Adhesive film for wafer backside grinding

10: First adhesive layer

20: Upper base material layer

30:Second adhesive layer

40: Lower base material layer

P: light scattering particles

Claims (13)

An adhesive film for wafer backside grinding, which includes: a multi-layer base material, including an upper base material layer and a lower base material layer; a first adhesive layer disposed on the upper base material layer; and a second adhesion layer disposed on Between the upper base material layer and the lower base material layer, the second adhesive layer is formed of an adhesive composition including a translucent adhesive resin and light scattering particles, and satisfies the following formula 1. The refractive index of the light scattering particles 1.42~1.60:

, in the formula 1, A is the refractive index of the translucent adhesive resin, and B is the refractive index of the light scattering particles, wherein, relative to 100 parts by weight of the adhesive composition of the second adhesive layer, 0.1 part by weight is included. to 10 parts by weight of the light scattering particles. For example, the adhesive film for wafer backside grinding in claim 1 has a total light transmittance of more than 70%. For example, the adhesive film for wafer backside grinding according to claim 1, wherein the diffuse transmittance is more than 6%. As claimed in claim 1, the adhesive film for wafer backside polishing, wherein the light scattering particles include at least one of inorganic particles and organic particles. For example, the adhesive film for wafer backside grinding according to claim 1, wherein the average particle size of the light scattering particles is 1 μm ~ 50 μm. An adhesive film for wafer backside grinding according to claim 4, wherein the inorganic particles include at least one selected from the group consisting of silicon dioxide particles, glass powder and quartz particles. Such as the adhesive film for wafer backside polishing in claim 4, wherein the organic particles include particles selected from the group consisting of acrylic resin particles, polystyrene resin particles, styrene-acrylic acid copolymer components, polyethylene resin particles, and epoxy resin particles. , silicone resin particles, polyvinylidene fluoride particles, polytetrafluoroethylene particles, divinylbenzene resin particles, phenol resin particles, urethane resin particles, cellulose acetate particles, nylon particles, cellulose particles, benzomelamine One or more of the group consisting of resin particles and melamine resin particles. For example, the adhesive film for wafer backside grinding of claim 1, wherein the thickness of the first adhesive layer is 10 μm ~ 100 μm, and the thickness of the second adhesive layer is 10 μm ~ 100 μm. The adhesive film for wafer backside grinding according to claim 1, wherein the lower base material layer and the upper base material layer respectively comprise polyethylene terephthalate, polyethylene naphthalate, polyethylene naphthalate, Butylene terephthalate, fully aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polystyrene, polyetherketone and bidirectional More than one member of the group consisting of stretched polypropylene. The adhesive film for wafer backside grinding according to claim 9, wherein the lower base material layer and the upper base material layer are formed of polyethylene terephthalate. The adhesive film for wafer backside grinding according to claim 1, wherein the first adhesive layer is formed of an adhesive composition containing an acrylic adhesive resin. The adhesive film for wafer backside grinding according to claim 1, wherein the translucent adhesive resin of the second adhesive layer includes a translucent acrylic adhesive resin. For example, in the adhesive film for wafer backside grinding of claim 1, the shear storage modulus of the second adhesive layer under a temperature condition of 30°C is 0.05MPa~5.00MPa.

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